The present invention relates generally to a method of geophysical exploration and more particularly to a method for transforming qualitative descriptors of seismic data into a quantifiable decision-making tool to obtain estimates of formation properties as well as to estimate the economic potential of selected formations for producing hydrocarbons.
Geophysical exploration of the earth's subsurface formations is most typically undertaken by recording seismic signals representative of the transmission and reflection properties of subsurface formations to seismic energy imparted into the earth. Initially, interpretation of displays of seismic signals was qualitative in nature and was generally limited to developing structural images of the earth's subsurface formations. Explorationists soon recognized that such seismic signals also contained quantifiable attributes (for example, frequency, amplitude, phase, etc.) which have been employed to evaluate subsurface formation structures as well as provide indications of changes in formation lithology and pore fluid content. Exemplary of such focus are Bodine et al. in U.S. Pat. No. 4,646,239, Hanson et al. in U.S. Pat. No. 4,755 972, Bodine in U.S. Pat. No. 4,779,237, and Barney in U.S. Pat. No. 4,967,401. In fact, only Bodine directly addressed explorationists' real interest of transforming the quantitative attributes of the seismic data into quantitative estimates of the earth's formation properties. In spite of such advances, the explorationist is still generally left with making qualitative assessments of the earth's formations from visual displays of seismic data.
Unlike most recent advances in geophysical exploration which attempt to obtain quantitative attributes of seismic signals to evaluate and distinguish subsurface formations, the present invention provides a novel technique for transforming qualitative descriptors of the seismic signals into estimated formation properties as well as a method to evaluate the economic potential of a formation for producing hydrocarbons.